The present invention relates to a document feeding device and a document reading apparatus comprising the same. More particularly, the present invention relates to a structure in the document feeding device which removes an inappropriately conveyed document.
A copier, a facsimile machine, a scanner apparatus, and the like comprise a document feeding device which delivers documents set on a sheet feeding tray, one by one, and which automatically feeds each of the documents with images onto a platen.
The document feeding device of this kind generally comprises a document conveying path through which each of the documents set on the sheet feeding tray is fed to a sheet discharging tray via the planar platen provided on a top surface of a main body of an image forming apparatus. The document conveying path often has a bent portion, and is thus formed substantially like a letter U, in order to discharge the document from the sheet feeding tray to the lower sheet discharging tray via the platen.
A guide cover is provided on the document conveying path and comprises a plurality of rollers that nips and feeds out the document. The guide cover is attached to a side plate so that the guide cover can be opened and closed using one end thereof as a support point. The guide cover can thus be opened to allow the removal of a document inappropriately conveyed on the document conveying path such as a jammed document, or to allow a maintenance operation such as cleaning to be performed.
With regards to means for removing the jammed document, Japanese Patent Laid-Open No. 9-86722 discloses a configuration in which the guide cover is opened to cancel the compression (nipping) of all rollers arranged on the document conveying path. Furthermore, Japanese Patent Laid-Open No. 2003-319131 discloses means for canceling the nipping of, among all the plurality of rollers on the document conveying path, a roller located immediately in front of the platen.
As shown in these conventional examples, the plurality of rollers arranged on the document conveying path is composed of a driving roller located inside the document conveying path and a driven roller located outside the document conveying path and abutting against the driving roller. The driven roller is attached to the guide cover, which covers the document conveying path. Thus, opening the guide cover allows the nipping between the driving roller and the driven roller to be easily cancelled. On the other hand, a part of the document conveying path which is located at a position immediately in front of the platen has only a small space. Thus, the nipping between the rollers arranged in this part may not be sufficiently cancelled. In particular, the part of the conveying path which is located at the position immediately in front of the platen has guide members that allow the document to travel along the conveying path in order to minimize the inaccuracy of reading of the image from the document. The guide members are arranged so as to have a gap with the minimum width that allows one sheet to pass through along the conveying path in order to prevent the document to be fed to the platen from being out of track.
If the document being conveyed is jammed, the nipping between the rollers can be cancelled by opening the guide cover. However, since the guide member is fixed to the part of the conveying path which is located at the position immediately in front of the platen, a leading end portion of the document may be caught in the gap, which allows the document to pass through. Thus, even when the nipping between the rollers is cancelled, the document may not be easily removed completely. In this condition, an attempt to forcibly remove the document may cause the leading end portion of the caught document to be torn. The leading end portion of the document may remain on the platen instead of being removed.
It is therefore an object of the present invention to provide a document feeding device which reliably guides a document to an image reading portion and which comprises a canceling configuration allowing the easy and reliable removal of the inappropriately conveyed document.
Further objects and advantages of the invention will be apparent from the following description of the invention.